JUNE 7.] THE NEW ZEALAND GAZETTE. 1469

generally called "red), but all which look reddish, scarlet, cinnabar, or sealing-wax red. This is of no importance, for those who only do this have scarcely such defective chromatic sense as that with which we are concerned.

Under any circumstances it is better to correct the mistakes just mentioned, when arising from misunderstanding, and it is even necessary, in reference to the mistakes we explained might occur with the first test. It might be said that it was sufficient if the examined confounded the test-colour with green only; that it was indifferent whether he distinguishes carefully between the various kinds of green. But, in fact, this is not so unimportant. We must give full weight as to whether the confusion arises from misunderstanding, or lack of practice with colours; or, finally, from a true chromatic defect. To include all that is green would render the test tedious and unpractical. In fact, no little judgment has been exercised in the selection of the very lightest shade of the green proposed as a test-colour, for it is exactly what the colour-blind most readily confounds with the colours (1–5) of the plate. If the examinee were allowed to depart from the narrow limits every shade of green could be included, the result of which would be that he would prefer to select all the vivid shades, and thus avoid the dangerous ground where his defect would certainly be discovered. This is why it is necessary to oblige him to keep within certain limits, confining him to pure-green specimens, and, for greater security, to recommend him to select especially the lightest shades; for, if he keeps to the darker shades, as many try to do, he readily passes to other tones, and loses himself on foreign grounds, to the great loss of time and of the certainty of the test. What we have just said of green applies also, of course, to purple (test IIa.).

The principle of our method is to force the examinee to reveal, by an act of his own, the nature of his chromatic sense.

Now, as this act must be kept within certain limits, it is evident that the Examiner must direct him to some extent. This may present, in certain cases, some difficulty, as he will not always be guided, and does either too much or too little. In both cases the Examiner should use his influence in order to save time and gain certainty, and this is usually very easily done. This intervention is, of course, intended to put the examinee in the true path, and is accomplished in many ways, according to the case in point.

We will here mention some of the expedients we have found useful :—

(A.) Interfering when the Candidate selects too many Colours.

It is not always easy to confine the candidate within the proper limits. In the first test he easily slips a yellow-green or blue-green skein among the others, and as soon as there is one others usually follow; and it thus happens that in a few moments he has a whole handful of yellow-green, a second of blue-green, a third of both these shades at the same time. Our procedure has assisted us in more than one case of this kind.

(a.) When the person examined has begun to select shades of one or several other colours than those of the sample, his ardour is arrested by taking from him the handful of skeins he has collected, and asking him whether his eye does not tell him there are some which do not match the others, in which case he is told he may restore them to the pile. He then generally proceeds in one of the following manners :—

1. He rejects, one after the other, the incorrect skeins, so that only the correct remain, which is often only the sample skein. He is shown what mistake he has made, and he is told only to select skeins of the same hue as the specimen, although they may be lighter or darker. If his first error arose only from a misconception, o’ want of practice in handling colours, he begins generally to understand what he has to do, and to do properly what is required of him.

2. Or else he selects and rejects immediately the test-skein itself. This proves that he sees the difference of colour. He is then shown the test-skein as the only correct one, and is asked to repeat the trial in a more correct manner. He is again put on the right track, as just before, and the trial proceeds rightly, unless the error arose from a defect in colour-sense. Many seem, however, to experience a natural difficulty in distinguishing between yellow-green and blue-green, or the dull shades of green and blue. This difficulty is, however, more apparent than real, and is corrected usually by direct comparison. If the method requiring the name of the colour to be given is used, a number of mistakes may be the result. If a skein of light-green and light-blue alone are presented to him, and he is asked to name them, he will often call blue green and green blue. But if, in the first case, a blue skein is immediately shown him, he corrects his mistake by saying, “This is blue and that green.” In the last case the same thing happens mutatis mutandis. This is not the place for an explanation. It must suffice to say that the error is corrected by a direct comparison between the two colours.

(b.) Another Process.—If the candidate place by the sample a shade, for instance, of yellow-green, the Examiner places near this another shade in which there is more yellow, or even a pure yellow, remarking at the same time that if the first suit the last must also. The candidate usually dissents from this. He is then shown, by selecting and classing the intermediate shades, that there is a gradation, which will diverge widely if logically carried out as he has begun. The same course is followed with colours of the blue shades, if the blue-green were first selected. He sees the successive gradations, and goes through with this test perfectly, if his chromatic sense is correct.

To ascertain further whether he notices the tints of yellow and blue in the green, we can ourselves take the yellow-green and blue-green and ask him if he sees any difference in colour between them. We can judge by his answer of his sense with regard to these shades, and the object of this investigation is accomplished.

It results from all this that many who are finally considered to have a normal chromatic sense may occasionally cause embarrassment. In the main, the normal observer of this kind causes greater loss of time than the colour-blind. It is astonishing to see with what rapidity the colour-blind betray their defect. At least, it is found in the majority of the cases examined by us that the first skein of wool selected from the pile by the colour-blind in the first test was one of the “colours of confusion.”

(B.) Interfering when the Candidate selects too few Wools.

Those who evince too great slowness also require the interference of the Examiner in another manner. We can lay aside here those cases in which, at the